John holland-letz



April 27 1926. 1 1,582,819

J. HoLLAND-LE-rz GRINDING BURR Filed July 28, 1924 H I B 5' E A.BX w/ l ATyr Patented Apr. 27, 1926.

UNITED STATES y PATENT OFFICE.

JOHN HOLLAND-LEITZ, 0F CROWN POINT, INDIANA, ASSIGNOR TO TI-IE LETZ MANU- FACTURING COMPANY, OF CROWN POINT, INDIANA, A CORPORATION 0F INDIANA.

GRINDING BURR.

Application led July 28, 1924.

My invention is concerned with burrs forv grinding mills, such as are used by farmers for grinding feed, and it is4 designed to produce a burr for coarse grinding that shall have a large capacity without requiring agreat deal of power to drive it, and which shall be capable of grinding a 'wide variety of feeds, such as ear corn, oats, corn husksf soy beans, hay and alfalfa.

To illustrate my invention, I annex hereto a sheet of drawings, in which the same reference characters are used to designate identical parts in all the figures, of which,-

Fig. 1 is aplan view of a. portion of a burr embodying my invention; and

Figs. 2, 3, A and 5 are views in section on the lines 2 2, 3-3, 4-4 and 5 5, respec tively.

In carrying out my invention, I employ a generally annular casting A preferably provided on its rear face with a pair of annular ribs B and C and the apertures Dvfor the bolts by which the burrs are secured in place.

rIhe grinding face is formed of a series, preferably four, of similar or substantially identical sections, and one of said sections may be considered as extending from one of the tearing teeth E illustrated to the other one. The burr may be considered as made up of the base or body portion, having the narrow outer face portion F, which is substantially fiat, with the inclined face portion Gr slanting downwardly therefrom to the open center. All of the teethproject upward from these surfaces F and G, and their fiat grindingsurfaces are all in the same plane, being formed by grinding off the tops of the teeth as they exist in the natural casting.

The tearing teeth E have their gi'indii'ig surfaces extending practically laterally across the ringand asa great strain is sometimes put on these teeth, I strengthen them by providing the generally triangular portion I-I back of them, which portion is not, slanted @E so sharply as the resi; the

P4., and P5; and Q, Q and Q2 Serial No. 728,628.

base portion G to give them a greater backing of metal. rIhe feeding teeth J also extend practically across the ring, and both they and the tearing and feeding` teeth E extend at a substantial angle to a radial line through either the point or the heel of the teeth.

Associated with the inclined tearing and feeding teeth E and the feeding teeth J, are the four feeding teeth K, K, K2 and K3, which are inclined to the radial lines passingthrough them even more than the teeth E and J, and which accordingly have a substantial feeding action although they do not extend entirely to the inner periphery of the ring. All these teeth K, K', K2 and K3 have their outer portions inclined at an angle to their smaller, inner portions, and their ground-olf, fiat shearing and grinding surfaces include the angle between the inner and outer portions. Another group of interposed teeth L, L', L2, L3, L4, L5, L6, L7, L8 and L9 may be called auxiliary feeding teeth, inasmuch as their pointed inner por tions below their grinding surfaces have that function to some extent. Said inner portions are designed to accommodate themselves to the spaces between the main feeding teeth, and with said main Vfeeding teeth to form channels through which the material may pass outward in a generally radial direction to the grinding teeth proper.

These grinding teeth proper are arranged in rows, consisting of the teeth M and M; N, N and N2; O, O, O2 and O3, P, F, P2, P3

the tearing teeth E; and of the teeth m and mi i 71: n, and 722i 07 0,7 027 03 047 05 i pip/Z727 p3 04 and p5; and q, g and g2 to the left of said teeth; and it will be noted that the grinding surfaces of the teeth L and K form a continuation of the m and m series; the grinding surfaces of the teeth L', L2 and K2 form a continuation 0f the n, n and a2 series; the grinding surfaces ofthe teeth L3 forma continuation of the o, o', 02, o3, otand o5 series; the grinding surfaces of the teeth L4L and K2 form a continuation of the M and M series; the grinding surfaces of the teeth L5,

to the right of v lli) tudinal axial line, such as the teeth a and m, 0 and n2, p and 02, p and 03, for instance, is almost as great as the length of the teeth, producing a faster feed than is possible where the teeth are closer together, as has been the practice heretofore. It will also be noted that the teeth of the different series, such as 0, o', 02, 03, o'i and 05, are staggered relative to the teeth of the adjacent series, such as 29, p', 792, p8, p4 and p5, thus requiring the material to travel in a zigzag path in getting to the outer periphery of the rings, and resulting in a more thorough grinding than if the material could pass outwardly in straight lines.

It will further be noted that the axes of all the grinding teeth in each of the eight groups are arallel to each other and also to a radial ine passing through the center of each group. This results in these grinding teeth having on one side of the radial line a slight tendency to feed the material outward, while on the other side of said radial. line a corresponding tendency to feed it backward or inward exists, this alternating action producing an intermittent or wave-like action that clears the burrs better than a uniform outward movement.

The operation of a pair of these burrs designed as above described can be seen Vfrom a study of the same. I have found by experience that for coarse grinding of a variety of feeding material, as above enumerated, these burrs have alarge capacity, practically double that of those they superseded, and furthermore that they produce a minimum of flour, which is very objectionable when ground feeds are fed dry, as it tends to get into the nostrils of the animals.

While I have shown and described my invention as embodied in the form which I at present consider best adapted to carry out its purposes, it will be understood that it is capable of some modifications, and that I do not desire to be limited in the interpretation of the following claims except as may be necessitated by the state of the prior art.

lVhat I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a grinding burr, the combination with an annular base, of a series of feeding teethlextending across the base at an angle to radial lines projected therethrough, and groups of grinding teeth, the axes of said grinding teeth in each group being substantially parallel to each other .and to a radial line projected through the center' of the group and said grinding teeth being short and so located that they form tangential lines of openings between the adjac-ent ends of the teeth.

2. In a grinding burr, the combination with an annular base, lof a series of feeding teeth extending across the base at an angle to radial lines projected therethrough, and a group of grinding teeth on the base, the axes of the grinding teeth in a group being substantially parallel to each other and to a radial line projected through the center of the group and said grinding teeth being short and so located that they form tangential lines of openings between the adjacent ends of the teeth.

3. In a grinding burr, the combination with an .annular base decreasing in thickness toward the inner periphery of the same, of grinding teeth on the face of the base, and a plurality of tearing teeth projecting inwardly beyond the general outline of the inner periphery, each of said tearing teeth having a backing in said base of greater thickness than the adjacent body of the base in advance of the teeth.

4c. In a grinding burr, the combination with an annular base, of a plurality of feeding .and tearing teeth extending entirely across the base and projecting inwardly beyond the general outlines of the inner periphery, a plurality of feeding teeth, all of said teeth extending in the same general direction relative to radial lines projected therethrough, and grinding teeth located outside of the feeding teeth, substantially as and for the purpose described.

5. In a grinding burr, the combination with an annular base, of a plurality of feeding and tearing teeth extending entirely across the base and projecting inwardly beyond the general outlines of the inner periphery, a plurality of feeding teeth, all of said teeth extending in the same general direction relative to radial lines projected therethrough, and groups of grinding teeth, the axes of said teeth in each group being substantially parallel to each other and to a radial lin-e projected through the center of the group.

6. In a grinding burr, the combination with an annular base, of a plurality of feeding and tearing teeth extending across the base and projecting inwardly beyond the general outlines of the inner periphery, a plurality of feeding teeth, all of said teeth extending in the same general direction relative to radial lines projected therethrough, and groups of grinding teeth, the axes of said teeth in each group being substantially parallel to each other and to a radial line projected through the center of the group, .some of said feeding teeth having portions extending outwardly therefrom parallel to the axes of the grinding teeth of the adjacent groups.

7. In a grinding burr, the combination with an annular base, of a plurality of feeding and tearing teeth extending across the base and projecting inwardly beyond the general outlines of the inner periphery, a plurality of feeding teeth, all of said teeth extending '1n the same general direction relaifi@ lil() tive to radial lines projected therethrough, and grinding teeth located outside of the feeding teeth and arranged in rows in staggered relationship to adjacent rows, substan-` tially as and for the purpose described.

8. In a. grinding burr, the combination with an annular base, of a plurality of feeding and tearing teeth extending across the base and projecting inwardly beyond the general outlines of the inner periphery, .a plurality of feeding teeth7 all of said teeth extending in theI same general direction relative to radial lines projected therethrough, and grinding teeth located outside the feeding teeth and arranged in rows in staggered relationship to .adjacent rows, the feeding teeth in some instances constituting continuations of the rows of grinding teeth, suhstantially as and for the purpose described.

In witness whereof, I have hereunto set 20 my hand.

JOHN HOLLAND-LETZ. 

